Cell Organelles and Reproduction

Major Cellular Organelles




Cell Membrane

Selective Barrier

Transport of cellular nutrients and waste

Recognition of cellular signals





Interior matrix of cell

Contains cellular molecules, macromolecules such as enzymes, lipids, carbohydrates, and RNA

Organized and compartmentalized





Largest organelle

Contains chromosomes

Chromosomes consist of DNA and Protein

Organized by protein matrix





Contains the Kreb cycle and electron transport system

Major site of ATP synthesis

Involved with cellular  “self destruct” called Apoptosis





Contains the Photosynthetic systems

Responsible for converting light energy to chemical energy





Composed of RNA and proteins

Responsible for synthesizing protein molecules





Contains digestive enzymes that break up proteins, lipids, and nucleic acids

Responsible for removing waste molecules and recycling molecular subunits
































Consider how some of these organelles interact:

GENE EXPRESSION:  nucleus- (DNA > gene > transcription produces m RNA > mRNA leaves through nuclear pore into cytosol> binds to ribosome and directs the synthesis of a protein.

CELL MEMBRANE : contains proteins that bind molecules > after binding, protein is endocytosed (http://www.sp.uconn.edu/~bi107vc/images/cell/clathrin.jpg) > protein releases the molecule and can be reused by exocytosis (reverse of endocytosis) or can be sent to lysozyme for degradation

CELL REPRODUCTON: many organelles are involved in cell reproduction, including the nucleus and the mitochondria and chloroplasts.  All of these organelles contain DNA that must be replicated so that each new cell will have complete copies.

Prokaryotic cells (bacteria) divide by:

1.     Duplicating their circular DNA molecule

2.     Attaching each DNA molecule to the cell membrane

3.     Adding membrane components between the attachments to separate the duplicated DNA molecules

4.     Using membrane fission (http://bio.winona.msus.edu/bates/genbio/images/fission.gif) to create two new bacteria cells

Eukaryotic cells divide by:

1.     Duplicating the chromosomes (chromosomes contain DNA and protein)

2.     Separating the duplicated chromosomes (Mitosis)

3.     Duplicating other organelles (mitochondria, chloroplast, etc)

4.     Reforming the nuclear envelope

5.     Laying down membrane components between the two nuclei (cytokinesis)

6.     Forming two new cells (http://genetics.gsk.com/graphics/mitosis-big.gif)




1)    Compare the rate of reproduction between a bacteria (simple asexual) and a eukaryotic cell (complex asexual) using www.cellsalive.com .  Students use graph paper to plot the growth curve and compare the two types of cells.




The web site Cells Alive.com has many resources for studying cells and cell structure.  The resource that we are going to utilize is the Cell Cam.  This resource consists of a video camera attached to a microscope that captures images of the cells and post those images to the web at given intervals.  These images show the growth of bacterial or eukaryotic cells over time. 


A conceptual method for teaching students the difference between prokaryotic and eukaryotic cells is for the students to answer the question:

Which cell type reproduces faster?

This question can be best answered by comparing the growth rates of the two different cell types.  Since it is difficult and costly to set up cell cultures, we will utilize the data from the Cell Cam to address this question.


Collecting the data from Cell Cam requires monitoring the web site over time.  In the bacterial cam, the frames are refreshed very minute whereas in the cancer cell cam, the frames are refreshed every 10 minutes.  A comparison between the two cell types will require monitoring the web site for at least 6 hours to collect data points that can be used to support a graph.  I have established a web site that has collected the images from the Cell Cams over a long time period and you can use this web site to supplement the activity.


Bacterial Cell Cam (note- the images were collected every 5 minutes)

Cancer Cell Cam (note- the images were collected every 10 minutes)


Items needed for activity:

·        Graph paper

·        Images from the cell cam.


2)    Examine maps of Mitochondrial, Chloroplast, and Genomic DNA using online resources (http://www.ncbi.nlm.nih.gov/)



To demonstrate the use of web based resources concerning DNA and biotechnology, we will examine using the NCBI (National Center for Biotechnology Information at

http://www.ncbi.nlm.nih.gov/).  We will compare the sizes and complexity of the mitochondrial and chloroplast genomes as an example of the types of information one can gather at this site.


·        First we can examine a map of the human mitochondrial DNA at http://www.ncbi.nlm.nih.gov/genomes/framik.cgi?db=Genome&gi=12188


·        You can use this type of image to show the students the minimum genes that are found on the human mitochondria.  Also, you can point out that for many of the mitochondrial proteins, other genes are located in the nucleus; thus it requires both sets of genomes to make functional mitochondria.  For example:

Mitochondrial Function

Genes on Mito DNA

Genes in Nucleus

Electron Transport

-NADH Dehydrogenase

-Cytochrome C oxidase

-2 subunits of ATP synthetase

-Cytochrome b

-Cytochrome c

-remaining subunits of ATP synthetase